I've successfully completed the Dark Brotherhood Questline in Skyrim and purchased the Poisoner's Nook Alchemy Table + Garden for the Sanctuary. However, it appears that the plants haven't yet grown back, which is a pity.

2 Answers
2

The cell reset time in Skyrim is a whopping 30 days according to what inspection of the ESM is so far possible with existing Fallout 3 tools. So rest assured, the nook's plants will regrow eventually, it'll just take a long while.

For those who think this is way too long for streets to be cleared of bodies and plants to regrow, there is already a mod to set the reset time to 1, 2, 3, or 7 days: Skyrim Respawn.